On
"Supernatural," lying is nothing new to the Winchesters -- in fact, this summer we spoke with writer Ben Edlund about
what makes Sam and Dean so prone to hiding the truth from each other. This season is no exception to the rule, but in this week's episode, "Blood Brother," Dean finds himself in a situation where he can no longer lie to Sam about his new comrade-in-arms, Benny the vampire.

"I liked the episode because I got to be on the water. Pirate vampires -- or as I like to call them, vampirates,"
Jensen Ackles joked while
Zap2itwas on set with him. It sounds fun, but as Dean's two worlds collide, things definitely get a little bit difficult, particularly because in some ways, the strength of Dean's relationship with Benny rivals his relationship with Sam.

"You hear these war stories of soldiers. You get a southern guy and a guy from New York, two completely opposite people, and they get tossed in a foxhole together and they come back closer than brothers," Jensen says, though he admits that the "closer than brothers" thing could be a bit of an exaggeration. "I wouldn't pretend to know exactly what kind of bonds are established in war, and I think that if I was to have an idea of what it is, I'm trying to emulate that with the relationship with Benny. These two guys have been through their personal hell and back."

One thing is for sure -- Jensen himself is having a blast in Season 8. Not only has it allowed him a more manageable schedule as he and costar Jared Padalecki shoot separately more often, but Benny has given Jensen fresh angles to play with a character about whom he thought he'd learned everything. "I think for a show going into its eighth season, curveballs like that are awesome," Jensen says. "I love the relationship that he's built with this monster. They have earned the respect of each other in such a foreign way."

In a lot of ways, Dean and Benny were both in their element in the Purgatory warzone, and now that they're on earth, they're just getting their sea legs. "I mean, obviously, it was live or die in Purgatory. He knew that he had a way out if he relied on this unlikely friend, and it happened to work out in his favor. Now that they've come topside, it's obviously a very strained situation, and they agree to kind of go their own ways but always have each others' back."

This week, Dean's loyalty is tested -- both his loyalty to Sam and his loyalty to Benny. "Benny essentially calls Dean and says, 'Hey, I'm in a sticky situation here, I could use a friend' and because of the relationship that was formed in Purgatory, Dean's like 'I gotta go,'" Jensen says. After so many years with the character, the decision rang true to Jensen. "I think that we all know that Dean's that guy. He's very loyal, but what's interesting is that his loyalty is now residing with a vampire, a monster ... and that obviously puts a strain on the relationship between the brothers. Sam even says 'You know, push comes to shove, I might be the one that kills Benny,' and Dean basically says, 'We'll cross that bridge when we get to it.'"

What we have yet to see, of course, is the way that Purgatory impacted Dean's relationship with Castiel, who was his only ally in the warzone when they first arrived. We know very little about what happened between those two men after they reunited. The one thing we can be sure of is that it didn't end well. Jensen can't offer too much insight for fear of giving too much away, but he
did reveal that there's something Castiel has been hiding from Dean.

"I will say that what I do know is that Cas is going through something that he's not telling Dean," Jensen teases. "He's going through something on a personal level, with himself and his own journey through Purgatory, that Dean is unaware of."

That'll be explored more thoroughly in Episode 8, but in the meantime, we turned to
Misha Collins for a little bit of elaboration on Castiel's mindset. Like Jensen, he can't say a whole lot. "Dean was hell-bent on getting the hell out of Purgatory, whereas Cas, I think, to a certain extent, felt so burdened with guilt that he felt like he was paying penance there," Misha tells us. "He felt that he almost deserved it."

And of course, because serious journalism is very important to us, we had to ask both men why Castiel had a beard in Purgatory and Dean did not. "Well, it's because he's an angel, and all of his badass angel powers were congregating into his hair follicles because of the intense pressure of the atmosphere in Purgatory," Misha says.

Jensen's response is a little bit different. "The answer I got from the writers was 'Dean has knives,'" he says.